Photographic element product composition and process

ABSTRACT

In a photographic diffusion transfer system a hydroquinone silver halide developing agent, containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus, provides reduced stain as well as improved maximum density, desired black tone, without loss of other desired sensitometric properties. Such developing agents, e.g. 6(2,5-dihydroxytolyl) hexanoic acid, are especially useful in a black and white silver salt diffusion transfer process. They can be incorporated in a photographic element and can be employed in combination with other silver halide developing agents.

United States Patent James G. Smith;

Dorothy J (Beavers, both of Rochester, N.Y. 20,790

Mar. 18, 1970 Oct. 26, 1971 Eastman Kodak Company Rochester, N.Y.

Inventors Appl. No. Filed Patented Assignee PHOTOGRAPHIC ELEMENT,PRODUCT,

[ References Cited UNITED STATES PATENTS 3,246,016 4/1966 Downey et al.96/29 3,345,166 10/1967 Land et al 96/29 Primary Examiner Norman G.Torchin Assistant Examiner.lohn L. Goodrow Allorneys-R. E. Knapp, W. H..l. Kline and B. D. Wiese ABSTRACT: In a photographic diffusion transfersystem a hydroquinone silver halide developing agent, containing amethyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl groupcontaining 4 to 9 carbon atoms in the 2 position of the hydroquinonenucleus, provides reduced stain as well as improved maximum density,desired black tone, without loss of other desired sensitometricproperties. Such developing agents, e.g. 6(2,5-dihydroxytolyl) hexanoicacid, are especially useful in a black and white silver salt diffusiontransfer process. They can be incorporated in a photographic element andcan be employed in combination with other silver halide developingagents.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to certain hydroquinone silver halide developing agents and tophotographic elements, processing compositions, and to processes andphotographic products, especially diffusion transfer systems, employingsuch developing agents. In one of its aspects it relates to aphotographic product containing a photographic element, a processingcomposition and an image receiver, in which product the described silverhalide developing agents are useful. In another of its aspects itrelates to a diffusion transfer process, especially a black and whitesilver salt diffusion transfer process, employing the describedhydroquinone silver halide developing agents.

2. Description of the Prior Art The processing composition usuallycontains a silver halide solvent such as sodium thiosulfate which causesthe unexposed silver salts usually silver halide to dissolve forming asilver complex which diffuses to the image receiver or precipitatinglayer where development nuclei for an image precipitating agent in thatlayer causes the silver to be precipitated from the silver compleximagewise. Development nuclei or precipitating agents can be present inthe imagereceiving layer before contact with the complex silver or thenuclei can be formed in situ. Diffusion transfer photographic processes,elements and compositions for such processes are well known anddescribed, for example, in U.S. Pat. No. 2,698,237 of Land issued Dec.28, 1954; U.S. Pat. No. 2,647,056 of Land issued July 28, 1953; U.S.Pat. No. 3,108,001 of Green issued Oct. 22, 1963; and U.S. Pat. No.3,345,166 of Land issued Oct. 3, 1967.

A processing composition employed in diffusion transfer processesnormally contains a developing agent and is usually applied as a viscousfluid layer spread between the photographic layer and theimage-receiving layer.

The requirements for developing agents for diffusion transfer systemsare very stringent and relatively few of the developing agents which aresatisfactory for general silver halide developing processes aresatisfactory or sufficiently active for diffusion transfer systems. Oneof the diffusion transfer developing agents used more successfully is a2,4- diaminophenol, such as 2,4-diaminophenol-dihydrochloride, alsoknown as Amidol. However, although such developing agents will produce apositive image they are subject to rapid oxidation which results in anunsightly and objectionable dark oxidation product which stains thepositive print.

Surprisingly, silver halide developing agents which have been employedsuccessfully in developing silver halide emulsions in generalphotographic processing have not provided the desired reduction instain, This is illustrated in the following examples 2,3 and 4 in whichit is demonstrated that catechol, 2,4-diaminophenol Amidol and t-butylhydroquinone silver halide developing agents do not provide a desiredreduction in stain, with a black tone image. Moreover, certain otherhydroquinone silver halide developing agents are not entirelysatisfactory. This is illustrated in example 5.

Accordingly, there has been a continuing need for develop ing agentswhich provide desired developing action and sensitometric properties ina diffusion transfer system, especially developing agents incorporatedin a photographic element, without objectionable stain or oxidationproducts.

SUMMARY OF THE INVENTION According to the invention, reduced stain,without loss of desired sensitometric properties, and a cold black imagetone are provided in a diffusion transfer system, employing photographicproducts, elements, processing compositions, and processes with ahydroquinone silver halide developing agent containing a methyl. ethylor alkoxy group, especially methoxy, ethoxy or propoxy, in the 5position and a carboxyalkyl group containing 4 to 9 carbon atoms, e.g.carboxypropyl, carboxybutyl or carboxypentyl, in the 2 position of thehydroquinone nucleus.

The hydroquinone silver halide developing agents, as described, areespecially suitable in a black and white silver salt diffusion transfersystem. Description of the Preferred Embodiments Suitable hydroquinonesilver halide developing agents which are employed in the practice ofthe invention include compounds of the formula:

I 0 z zCH2(CH2)nCO0H R1 wherein R is methyl, ethyl, or alkoxy,especially alkoxy containing l to 5 carbon atoms, e.g. methoxy, ethoxy,propoxy, butoxy or pentoxy; n is 0 to 5; R1 is alkyl containing 1 to 5carbon atoms, i.e. methyl, ethyl, propyl, butyl or pentyl, hydrogen orhalogen, especially chlorine, bromine, or iodine. Examples of suchcompounds within formula l include:

Z-carboxypropyl-S-methyl hydroquinone 2-carboxybutyl-5-methylhydroquinone 2-carboxypentyl-5-methyl hydroquinone2-carboxypropyl-5-ethyl hydroquinone 2-carboxypropyl-5-methoxyhydroquinone 2-carboxypropyl-5'carboxypropyl hydroquinone2-carboxypropyl-5,6-dimethy1 hydroquinone One embodiment of theinvention is: in a photographic product comprising in combination (a) aphotographic element comprising a photographic silver halide, (b) aprocessing composition containing a silver halide solvent and (c) animage-receiving layer, the improvement comprising in said photographicelement a hydroquinone silver halide developing agent containing amethyl, ethyl, or alkoxy group in the 5 position and a carboxyalkylgroup containing 4 to 9 carbon atoms in the 2 position of thehydroquinone nucleus.

Especially suitable hydroquinone developing agents useful in thepractice of the invention are those within the scope of the describedstructure.

The described silver halide location agents can be employed in thepractice of the invention in a range of physical locations in adiffusion transfer photographic system. However, they are especiallysuitable when incorporated in the negative photographic element. Thedeveloping agents can be employed, however, in a processing compositionemployed in such a system if desired. The optimum location will dependupon several factors such as the desired image, processing conditionsand the like. For example, the described silver halide developing agentscan be employed in a processing composition such as an aqueous alkalinedeveloper solution and/or they can be incorporated into one or morelayers of a photographic element such as a photographic silver halideemulsion layer, a layer between the support and the silver halideemulsion layer and/or an overcoat layer. Suitable diffusion transfersystems, processes, processing compositions and elements therefor whichcan be employed in the practice of the invention are described, forexample, in U.S. Pat. No. 2,352,014 of Rott issued June 20, 1944; U.S.Pat. No. 2,452,181 of land issued Feb. 27, 1951; and U.S. Pat. No.3,337,342 of Green issued Aug. 27, 1967. They can be used in so-calledhigh-speed diffusion transfer processes and compositions therefor asdescribed, for example, in U.S. Pat. No. 3,326,683 of Land et al. issuedJune 20, 1967 or in other types of diffusion transfer systems, processesand compositions therefor such as described in U.S. Pat. No. 2,857,274of Land et al. issued Oct. 21, 1958; U.S. Pat. No. 3,020,155 of Yackelet al. issued Feb. 6, 1962; U.S. Pat. No. 2,584,030 of Land issued Jan.29, 1952; and U.S. Pat. No. 2,923,623 of Land issued Feb. 2, 1960.

These references also describe typical photographic products suitablefor diffusion transfer systems comprising in,c ombination (a) aphotographic element comprising a photographic silver salt layer such asa photographic silver halide emulsion layer, (b) a processingcomposition containing a silver halide solvent and typically a silverhalide developing agent, e.g. in a rupturable container, and (c) animage receiver.

The developing agents employed in the practice of the invention can beemployed for developing an image in a wide range of photographicemulsions. They can be employed in such emulsions if desired.

The silver halide emulsions employed with this invention can comprisesilver chloride, silver bromide, silver bromoiodide, silverchlorobromoiodide, or mixtures thereof. The emulsions can be coarse orfine grain and can be prepared by any of the well-known proceduresemployed in emulsion making such as single-jet emulsions, double-jetemulsions such as Lippmann emulsions, ammoniacal emulsions, thiocyanateor thioether ripened emulsions, such as those described in U.S. Pat. No.2,222,264 of Nietz et al. issued Nov. 19, 1940; U.S. Pat. No. 3,320,069of lllingsworth issued May 16, 1967; and U.S. Pat. No. 3,271,157 ofMcBride issued Sept. 6, 1966. Surface image emulsion can be used orinternal image emulsions such as those described in U.S. Pat. No.2,592,250 of Davey et al. issued Apr. 8, I952; U.S. Pat. No. 3,206,313of Porter et al. issued Sept. 14, I965; U.S. Pat. No. 3,367,778 ofBerriman et al. issued Feb. 6, 1968; and U.S. Pat. No. 3,447,927 ofBacon et al. issued June 3, 1969. If desired mixtures of surface andinternal image emulsions can be used as described in U.S. Pat. No.2,996,382 of Luckey et aI. issued Aug. 15, 1961. Negative type emulsionscan be used or direct positive emulsions, such as those described inU.S. Pat. No. 2,184,013 of Leermakers issued Dec. 19, I939; U.S. Pat.No. 2,541,472 of Kendall et al. issued Feb. 13, I951; U.S. Pat. No.3,367,778 of Berriman et al. issued Feb. 6, 1968; British Pat. No.723,019 of Schouwenaars; French Pat. No. 1,520,785 published March 4,I968; U.S. Pat. No. 2,563,785 of Ives issued Aug. 7, I951; U.S. Pat. No.2,456,953 of Knott et al. issued Dec. 21, 1948; and U.S. Pat. No.2,861,885 of Land issued Dec. 8, I953.

The emulsions used with this invention can be sensitized with chemicalsensitizers such as with reducing agents; sulfur, selenium or telluriumcompounds; gold, platinum or palladium compounds; or combinations ofthese.

Suitable procedures for chemical sensitization are described in U.S.Pat. No. 1,623,499 of Sheppard issued Apr. 5, 1967; U.S. Pat. No.2,399,083 of Waller et al. issued Apr. 23, 1946; U.S. Pat. No. 3,297,447of McVeigh issued Jan. 10, 1967; and U.S. Pat. No. 3,297,446 of Dunnissued Jan. 10, I967.

The silver halide emulsions, processing compositions and/or imagereceivers used in the practice of the invention can contain speedincreasing compounds such as polyalkylene glycols, cationic surfaceactive agents and thioethers or combinations of these as described inU.S. Pat. No. 2,886,437 of Piper issued May 12, I959; U.S. Pat. No.3,046,134 of Dann et al. issued July 24, I962; U.S. Pat. No. 2,944,900ofCarroll et al. issued July 12, 1960; and U.S. Pat. No. 3,294,540of'Goffe issued Dec. 27, 1966.

The silver halide emulsions and image receivers used in the practice ofthe invention can be protected against the production of fog and can bestabilized against loss of sensitivity during keeping. Suitableantifoggants and stabilizers each used alone or in combination includethiazolium salts described in U.S. Pat. No. 2,131,038 of Brooker et al.issued Sept. 27, 1938 and U.S. Pat. No. 2,694,716 of Allen issued Nov.16, 1964; the azaindenes described in U.S. Pat. No. 2,886,437 of Piperissued May 12, 1959 and U.S. Pat. No. 2,444,605 of Heimbach issued July6, 1948; the mercury salts as described in U.S. Pat. No. 2,728,663 ofAllen et al. issued Dec. 27, 1955; the urazoles described in U.S. Pat.No. 3,287,135 of Anderson issued Nov. 22, 1966; the sulfocatecholsdescribed in U.S. Pat. No. 3,236,652 of Kennard et al. issued Feb. 22,1966; the oximes described in British Pat. No. 623,448 published May 19,

I949; nitron; nitroindozoles; the mercaptotetrazoles described in U.S.Pat. No. 2,403,927 of Kendall et al. issued July 16, I946, U.S. Pat. No.3,266,897 of Kennard et al. issued Aug. 16, 1966 and U.S. Pat. No.3,397,987 of Luckey et al. issued Aug. 20, 1968; the polyvalent metalsalts described in U.S. Pat. No. 2,839,405 of Jones issued June 17,1958; the thiuronium salts described in U.S. Pat. No. 3,220,839 of Hertzissued Nov. 30, 1965; the palladium, platinum and gold salts describedin U.S. Pat. No. 2,566,263 of Trivelli et al. issued Aug. 28, 1951 andU.S. Pat. No. 2,597,915 of Yutzy et al. issued May 27, I952.

The photographic and other hardenable layers employed in a photographicelement or image receiver in the process of this invention can behardened by various organic or inorganic hardeners, alone or incombination, such as the aldehydes and blocked aldehydes, ketones,carboxylic and carbonic acid derivatives, sulfonate esters, sulfonylhalides and vinyl sulfones, active halogen compounds, epoxy compounds.azaindenes, active olefins, isocyanates, carbodiimides, mixed functionhardeners and polymeric hardeners such as oxidized polysaccharides likedialdehyde starch, oxyguargum and the like.

The photographic emulsions and elements including image receiversdescribed, employed in the practice of this invention, can containvarious colloids alone or in combination as vehicles, binding agents andvarious layers. Suitable hydrophilic materials including both naturallyoccurring substances such as proteins, for example, gelatin, gelatinderivatives, cellulose derivatives, polysaccharides such as dextran, gumarabic and the like; and synthetic polymeric substances such aswater-soluble polyvinyl compounds like poly(vinylpyrrolidone),acrylamide polymers and the like.

The described photographic emulsion layers, image receivers and otherlayers of a photographic element employed in the practice of thisinvention can also contain, alone or in combination with hydrophilic,water-permeable colloids, other synthetic polymeric compounds such asdispersed vinyl compounds, such as in latex form and particularly thosewhich increase the dimensional stability of the photographic materials.Suitable synthetic polymers include those described, for example, inU.S. Pat. No. 3,142,568 of Nottorfissued July 28, 1964; U.S. Pat. No.3,193,386 of White issued July 6, I965; U.S. Pat. No. 3,062,674 of Houcket al. issued Nov. 6, I962; U.S. Pat. No. 3,220,844 of Houck et al.issued Nov. 30, 1965; U.S. Pat. No. 3,287,289 of Ream et al. issued Nov.22, 1966; and U.S. Pat. No. 3,411,911 of Dykstra issued Nov. 19, I968.Particularly effective are those water insoluble polymers of alkylacrylate and methacrylate, acrylic acid, sulfoalkylacrylates ormethacrylates, those which have cross-linking sites which facilitatehardening or curing and those having recurring sulfobetaine units asdescribed in Canadian Pat. No. 774,054.

The photographic elements and image receivers used in the practice ofthe invention can contain antistatic or conducting layers. Such layerscan comprise soluble salts such as chlorides, nitrates and the like,evaporated metal layers, ionic polymers such as those described in U.S.Pat. No. 2,861,056 of Minsk issued Nov. 18, 1958 and U.S. Pat. No.3,206,312 of Sterman et al. issued Oct. 14, 1965 or insoluble inorganicsalts such as those described in U.S. Pat. No. 3,428,451 of Trevoyissued Feb. 18, 1969.

The photographic elements, and/or image receivers and other layers of aphotographic element employed and described herein can be coated on awide variety of supports. Typical supports include cellulose nitratefilm, cellulose ester film, poly(vinylacetal) film, polystyrene film,poly(ethylene terephthalate) film, polycarbonate film, and related filmsor resinuous materials, as well as glass, paper metal and the like.Typically a flexible support is employed, especially a paper support,which can be partially acetylated or coated with baryta and/or an alphaolefin polymer, particularly a polymer of an alpha olefin containing 2to 10 carbon atoms such as polyethylene, polypropylene, ethylene-butenecopolymers and the like.

The photographic layers and/or image receiver layers employed in thepractice of this invention can contain plasticizers and lubricants suchas polyalcohols, e.g. glycerin and diols of the type described in U.S.Pat. No. 2,960,404 of Milton issued Nov. 15, 1968; fatty acids or esterssuch as those described in U.S. Pat. No. 2,588,765 of Robijns issuedMar. 1 1, 1952 and U.S. Pat. No. 3,121,060 of Duane issued Feb. 11, 1964and silicon resins such as those described in British Pat. No. 955,06 l.

The photographic layers, processing compositions and/or image receiversemployed in the practice of this invention can contain surfactants suchas saponin, anionic compounds such as alkyl or aryl sulfonates describedin U.S. Pat. N 0. 2,600,831 of Baldsiefen issued June 17, 1952 andamphoteric compounds such as those described in U.S. Pat. No. 3,133,816of Nen-Ezra issued May 19, 1964 and water-soluble adducts of glycidoland an alkyl phenol such as described in British Pat. No. 1,022,878.

The photographic elements and/or image receivers used in the practice ofthe invention can contain brightening agents including stilbene,triazene, oxazole, and coumarin brightening agents. Water-solublebrightening agents can be used such as those described in German Pat.No. 972,067 and U.S. Pat. No. 2,933,390 of McFall et al. issued Apr. 19,1960 or dispersions of brighteners can be used, such as those describedin German Pat. No. 1,150,274 and U.S. Pat. No. 3,406,070 of Oetiker etal. issued Oct. 15, 1968 and French Pat. No. 1,530,244.

The light-sensitive silver halide emulsions employed in the practice ofthe invention can be X-ray or other nonspectrally sensitized emulsions.They also can contain spectral sensitizing dyes and be convenientlyorthosensitized or pansensitized with such dyes. For instance, theseemulsions can be spectrally sensitized by treating with a solution of asensitizing dye in an organic solvent or the dye can be added in theform of a dispersion as described in British Pat. No. 1,154,781 of Owenset al. For optimum results, the dye may either be added to the emulsionas a final step or at some earlier stage. Sensitizing dyes useful insensitizing such emulsions are described, for example, in U.S. Pat. No.2,526,632 of Brooker et al. issued Oct. 24, 1950; U.S. Pat. No.2,503,776 of Sprague issued Apr. 11, 1950; U.S, Pat. No. 2,493,748 ofBrooker et a1. issued .Ian. 10, 1950; and U.S. Pat. No. 3,384,486 ofTaber et al. issued May 2 l, 1968. Spectral sensitizers which can beused include the cyanines, merocyanines, complex (trinuclear ortetranuclear) merocyanines, complex (trinuclear or tetranuclear)cyanines, homopolar cyanines, styryls, and hemicyanines, e.g. enaminehemicyanines, oxonols and hemioxonols. The cyanines can contain suchbasic nuclei as thiazolines, pyrrolines, pyridines, oxazoles, thiazoles,sclenazoles and imidazoles.

Such nuclei can contain sulfoalkyl; carboxyalkyl and alkylamino groupsand can be fused to benzene or naphthalene rings either unsubstituted orsubstituted with halogen, phenyl, alkyl or alkoxy groups. The dyes canbe symmetrical or unsymmetrical and can contain alkyl, phenyl orheterocyclic substituents on the polymethine chain. The merocyanine dyescan contain the basic nuclei mentioned as well as acid nuclei such asthiohydantoins, rhodanines, oxazolidenediones, barbituric acids,thiazolineones and malononitrile.

These acid nuclei can be substituted with alkyl, alkylene, phenyl,carboxyalkyl, sulfoalkyl, hydroxyalkyl, alkoxyalkyl, alkylamino groupsor heterocyclic nuclei.

Combinations of these dyes can be used, if desired.

In addition, supersensitizing addenda which do not absorb visible lightcan be included, for instance, ascorbic acid derivatives, azaindenes,cadmium salts, and organic sulfonic acids as described in U.S. Pat. No.2,933,390 of McFall et al. and U.S. Pat. No. 2,937,089 Of Jones et al.issued May 17, 1960.

The various addenda including sensitizing dyes employed in the practiceof this invention can be added to the photographic emulsions and/orother layers of a photographic element and/or image receiver from watersolutions or suitable organic solvent solutions. The compounds can beadded using various procedures including those described in U.S. Pat.No.

2,912,343 of Collins et al. issued Nov. 10, 1959; U.S. Pat. No.3,342,605 of McCrossen et a1. issued Sept. 19, 1967; U.S. Pat..,. No.2,996,287 of Audran issued Aug. 15, 1961 and U.S. Pat. No. 3,425,835ofJohnson et al. issued Feb. 4, 1969.

The layers of a photographic element and/or image receiver used in thepractice of the invention can be coated by various coating proceduresincluding dip coating, airknife coating, curtain coating, or extrusioncoating using hoppers of the type described in U.S. Pat. No. 2,681,294ofBeguin issued June 15, 1954. 11 desired, two or more layers can becoated simultaneously by the procedures described in U.S. Pat. No.2,761,791 of Russell issued Sept. 4, 1956 and British Pat. N 0. 837,095.

The described developing agents can be employed in color image transferprocesses, such as described in U.S. Pat. No. 3,087,817 of Rogers issuedApr. 30, 1963; U.S. Pat. No. 3,185,567 of Rogers issued May 25, 1965;U.S. Pat. No. 2,983,606 of Rogers issued May 9, 1961; and U.S. Pat. No.3,253,915 of Wyers issued May 31, 1966; U.S. Pat. No. 3,227,550 ofWhitmore et al. issued Jan. 4, 1966; U.S. Pat. No. 3,227,551 of Barr eta1. issued Jan. 4, 1966; US. Pat. No. 3,227,552 of Whitmore issued Jan.4, 1966 as well as U.S. Pat. Nos. 3,415,644; 3,415,645; and U.S. Pat.No. 3,415,646 of Land issued Mar. 10, 1967 and inhibition transferprocesses as described in U.S. Pat. No. 2,882,156 of Minsk issued Apr.14, 1959.

The described developing agents employed in the practice of theinvention can be used in colloid transfer processes. They can also beused in photographic elements and/or in processing compositions intendedfor use in monobath processing such as described in U.S. Pat. No.2,875,048 of Haist et al. issued Feb. 24, 1959 and British Pat. No.1,063,844 of Beavers et al. published Mar. 30, 1967.

The described developing agents employed in the practice of theinvention can also be used in multilayer, single element diffusiontransfer systems which utilize undeveloped silver halide in nonimageareas of a negative to form a positive by physical development of thissilver onto a nuclei-containing, contiguous, image-receiving layer afterwhich the upper layer is removed by scrubbing, washing, stripping orother suitable methods. Processes of this type are described, forinstance, in U.S. Pat. No. 3,020,155 of Yackel et al. issued Feb. 6,1962. Good results are obtained in elements of this type when they areprocessed by use of a so-called external processing web containing thedescribed developing agents in combination with a silver halide solventand other processing or coating components dispersed in a vehicle andcoated on a suitable support.

Processing webs of this type are described, for example, in U.S. Pat.No. 3,179,517 ofTregillus et al. issued Apr. 20 1965.

The developing agents employed in the practice of the invention can beemployed if desired in photographic elements designed for stabilizationtype processing. For example, they can be incorporated in one or morelayers of a photographic element which is exposed, and then processed bycontact with an alkaline development activator, and followed bystabilization with a suitable stabilizer such as a thiocyanate orthiosulfate stabilizer, e.g. by contact with a thiocyanate orthiosulfate solution containing ammonium thiocyanate or sodiumthiosulfate. Such processes are described, for example, in U.S. Pat. No.3,326,684 of Nishio et al. issued June 29 1967; British Pat. No.1,004,302 of llford published Sept. 15, 1965; French Pat. No. 1,516,556of Fassbender; and in an article by H. D. Russell et al. in P.S.A.Journal, Volume 8, No. 50, pages 59-62, entitled StabilizationProcessing of Films and Papers.

The developing agents employed in the practice of the invention can alsobe present in one or more layers of a photographic element designed forrecording color images. For example, these compounds can be employed inone or more layers of the photographic element containing a photographiclayer sensitive to the blue region of the spectrum, a photo graphiclayer sensitive to the green region of the spectrum, and a photographiclayer sensitive to the red region of the spectrum. Layers sensitive tothe blue, green and red regions of the spectrum can contain any suitablesensitizing dyes. Photographic elements designed for recording colorimages in which the developing agents of the invention can be used aredescribed, for example, in Mees, The Theory of the Photographic Process,Third Edition, pages 382-396 (1966).

The developing agents employed in the practice of the invention can beemployed in an element containing development nuclei or silverprecipitating nuclei, such as an image receiver. As described, they canalso be employed in photographic elements and/or processing compositionsdesigned for use with an image receiver.

Development nuclei or silver precipating agents which can be employed indiffusion transfer systems, as described, can be physical developmentnuclei or chemical precipitants including, for example: (a) heavy metalsin colloidal form and salts of these metals, (b) salts of amines whichform silver salts and/or (c) nondiffusing polymeric materials withfunctional groups capable of combining with silver amines.

Suitable development nuclei and/or silver image precipitating agentswithin the described classes include metal sulfides, selenides,polysulfides, polyselenides, thiourea and its derivatives, stannoushalides, sulfur, gold, platinum, palladium, and mercury, colloidalsulfur, aminoguanidine sulfate, aminoguanidine carbonate, arsenousoxide, sodium stannite, hydrazines, xanthates and similar agentsdisclosed, for example, in U.S. Pat. No. 3,020,l55 of Yackel et al.issued Feb. 6, 1962. A nondiffusing polymeric silver precipitant ordevelopment nuclei, such as poly(vinylmercaptoacetate) can also beemployed.

A wide range of concentration of development nuclei or silverprecipitating agents can be employed. A concentration of the developmentnuclei or silver precipitant in the image receiving layer must be atleast sufficient to insure the development ofa positive image andsufficient removal of undeveloped silver salt from the light-sensitivelayer to be processed. Usually the concentration of the developingagents, as described, is about 320 milligrams per square foot of thelayer containing the precipitants or development nuclei.

The development agents employed in the practice of the invention can beemployed in combination with other silver halide developing agents. Thedeveloping agents employed in the practice of the invention can beemployed in such combinations as auxiliary developing agents or as themain component of the developing agent combination. Suitable silverhalide developing agents which can be employed in combination with thedescribed developing agents include, for example, polyhydroxybenzenessuch as hydroquinone developing agents, e.g. hydroquinone, tertiarybutyl hydroquinone; catechol and pyrogallol; chloro substitutedhydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxysubstituted hydroquinones such as methoxyhydroquinone orethyoxyhydroquinone; aminophenol developing agents such as2,4-diaminophenols and methoxy aminophenols, methylaminophends; eq.6-methoxy- 2,4 -diaminophenolascrobic acid developing agents such asascorbic acid, ascorbic acid ketals, and ascorbic acid derivatives suchas those described in U.S. Pat. No. 3,337,342 OfGreen issued Aug. 22,1967; hydroxylamine developing agents such as N,N-di(2-ethoxyethyl)hydroxylamine; 3-pyrazolidone developing agents such asl-phenyl-3 3-pyrazolidone and l-phenyl-4- hydroxymethyl-3-pyrazolidone,including those described in British Pat. No. 930,572 published July 3,1963. Such developing agents can be used alone or in combination. It isusually desirable to use other developing agents than aminophenolcompounds because of the tendency of these compounds to cause undesiredstain.

The described developing agents are especially useful in combinationwith a reductone silver halide developing agent, especially an anhydrodihydro amino reductone silver halide developing agent. A range ofreductone silver halide developing agents can be employed in thepractice of the invention. These include any reductone silver halidedeveloping agents which provide desired developing activity andreduction of stain without adversely afiecting desired maximum density,minimum density, photographic speed, gamma and other desiredsensitometric properties. A suitable method for preparing the describedamino hexose reductones and anhydro amino hexose reductones is set outin U.S. Pat. No. 2,936,308 of Hodge issued May 10, 1960. Correspondinganhydro dihydro amino reductones can be prepared from correspondinganhydro amino reductones by a process of hydrogenation in the presenceof a suitable catalyst such as Raney nickel. This is described, forexample, in Tetrahedron, Volume 6, pages l23-l38 (1959). Especiallysuitable reductone silver halide developing agents are anhydro dihydropiperidino hexose reductone, anhydro dihydro pyrrolidino hexosereductone; and anhydro dihydro morpholino hexose reductone.

A variety of cinnamic acid silver halide developing agents can beemployed in combination with the described silver halide developingagents in the practice of the invention. Suitable cinnamic aciddeveloping agents include, for example:

Beta-4-dimethyl-2,S-dihydroxy cinnamic acid 4-methyl-2,5-dihydroxycinnamic acid 6-bromo4-methyl-2,S-dihydroxy cinnamic acid2-hydroxy-5-amino cinnamic acid Beta-methyl-2-hydroxy-4-methoxy-5-aminocinnamic acid Beta-4-dimethyl-Z-hydroxy-S-amino cinnamic acidBeta-metyl-2,5-dihydroxy-4-methoxy cinnamic acid 2-hydroxy-5-methylaminocinnamic acid 2-hydroxy-5-anilino cinnamic acid 4-! -butyl-2,5-dihydroxycinnamic acid 2,5-dihydroxy cinnamic acid 2,5-dihydorxy-3,4,6-trimethylcinnamic acid 2,3-dihydroxy cinnamic acid Cinnamic acid silver halidedeveloping agents in a diffusion transfer system are described, forexample, in U.S. application Ser. No. 764,301 ofOftedahl filed Oct. l,1968.

Typically the described cinnamic acid silver halide developing agentsare derived from corresponding hydroxycoumarin and/or aminocoumarindeveloping agent precursors.

Suitable aminocoumarin and/or hydroxycoumarin developing agents ordeveloping agent precursors which can be employed in the practice of theinvention include, for example:

4,7-dimethyl-6-hydroxy coumarin 8-hydroxy coumarin6-hydroxy-5,7-dimethoxy coumarin 6-hydroxy-5,7-diethoxy-4-methylcoumarin 6-hydroxy coumarin 8-hydroxy- 4-methyl coumarin 6-hydroxy-4-methyl coumarin 6-hydroxy coumarin-S-sulfonic acid 6-hydroxycoumarin-S-sulfinic acid 4,7,8-trihydroxy coumarin 5,6,7trihydroxy-4-methyl coumarin 6,7,8-trihydroxy-4methyl coumarin 5,6,7-trihydroxy-4-phenyl coumarin 4,6-dihydroxy coumarin 5,6-dihydroxycoumarin 6,7-dihydroxy coumarin 7,8-dihydroxy coumarin 7-(benzyloxy)-6-hydroxy coumarin 3,8-dibromo-6,7-dihydroxy-4-metyl coumarin5 ,6-dihydroxy-4,7-dimethyl coumarin 7,8-dihydroxy-3,4-dimethyl coumarin6,7-dihydroxy-4-methyl coumarin 7,8-dihydroxy-4-methyl coumarin6,7-dihydroxy-4-methyl-3-phenyl coumarin 6,7-dihydroxy-4-phenyl coumarinA variety of pyrimidine silver halide developing agents can also beemployed in the practice of the invention in combination with thedescribed silver halide developing agents. Suitable pyrimidine silverhalide developing agents include, for example:

4-amino-5,6-dinydroxy-2-methylpyrimidine2,5-dihydroxy-4,tS-dimethylpyrimidine 9 2-amino-4,S-dihydroxypyrimidine2-piperidino-4,5-dihydroxy-6-methylpyrimidine2,4-diamino-5-hydroxy-6-ethylpyrimidine 2,4-diamino-S-hydroxypyrimidine2,5-diamino-4,o-dihydroxypyrimidine 2,4-dihydroxy-5,6-diaminopyrimidine2,4,6-trihydroxy-S-diaminopyrimidine 2,4,5,6-tetrahydroxypyrimidine2-methyl-4-amino-5,fi-dihydroxypyrimidine2-amino-4,5-dihydroxy-6-methylpyrimidine2,4,5-trihydroxy-6-methylpyrimidine 2,4,5-triaminopyrimidine Pyrimidinesilver halide developing agents are described,

for example, in an article by R. W. Henn and S. V. Carpenter,Photographic Science and Engineering, No. 3, May-June, pages 135-139(1959). Pyrimidine silver halide developing agents can be prepared, forexample, by reacting the parent pyrimidine compound with a persulfatecompound such as ammonium persulfate to produce a S-pyrimidyl hydrogensulfate compound which can be hydrolyzed with acid such as concentratedhydrochloric acid to form a pyrimidine silver halide developing agentsuch as a S-hydroxypyrimidine.

Another embodiment of this invention is a photographic elementcomprising a support, photographic silver halide, and a hydroquinonesilver halide developing agent containing a methyl, ethyl or alkoxygroup in the 5 position and a carboxyalkyl group containing 4 to 9carbon atoms in the 2 position of hydroquinone nucleus, as described. Anespecially suitable hydroquinone developing agent is one of formula I,as described.

Another embodiment of the invention is in a photographic processingcomposition comprising (a) a silver halide solvent and (b) a silverhalide developing agent, the improvement comprising a hydroquinonesilver halide developing agent containing a methyl, ethyl or alkoxygroup in the 5 position and a carboxyalkyl group containing 4 to 9carbon atoms in the 2 position of the hydroquinone nucleus, asdescribed. This composition is especially suitable when an anhydrodihydro reductone silver halide developing agent, as described, is alsoemployed in the composition. A cinnamic acid silver halide developingagent, a coumarin silver halide developing agent or developing agentprecursor can also be employed in the described combination ofdeveloping agents in the processing composition.

This processing composition is typically employed in a combination of(a) a photographic element comprising a photographic silver salt,especially photographic silver halide, (b) a viscous processingcomposition comprising:

1. a silver halide solvent,

2. an alkaline development activator, and

3. a silver halide developing agent, and (c) an image receiving layercomprising development nuclei, especially palladium development nuclei,dispersed in a polymeric binder, wherein the improvement comprisesemploying a hydroquinone developing agent, as described, especially ahydroquinone developing agent of formula I in the photographic element.

Good results are obtained when the described hydroquinone developingagents according to the invention are employed in combination with anamino alkyl hydroquinone silver halide developing agent. The amino alkylhydroquinone silver halide developing agent is especially suitable whenincorporated in the described photographic element. Amino alkylhydroquinone silver halide developing agents which are suitable in thepractice of the invention include, for example, aminomethyl hydroquinonesilver halide developing agents of the formula:

wherein R R R and R are each hydrogen; alkoxy, especially alkoxycontaining 1 to 5 carbon atoms, such as methoxy, ethoxy, propoxy, butoxyor pentoxy; alkyl, especially alkyl containing 1 to 5 carbon atoms, suchas methyl, ethyl, propyl, butyl or pentyl; or aminomethyl, i.e.

wherein R and R are each hydrogen, alkyl, especially alkyl containing lto 5 carbon atoms, as described, aryl containing 6 to 20 carbon atoms,such as phenyl, tolyl and xylyl or together are atoms completing aheterocyclic nucleus, especially a 5 or 6 atom heterocyclic nucleus suchas morpholino, piperazino, piperidino, pyrrolidino, 4-methyl piperidinoand the like; at least one of R R R, and R is aminomethyl as described.

Corresponding amino alkyl catechol silver halide develop ing agents arealso suitable in combination with the described hydroquinone silverhalide developing agents in the practice of the invention. These includecompounds corresponding to the described hydroquinone compounds offormula ll wherein the hydroxy groups are in the ortho position ratherthan the para position.

Suitable aminomethyl hydroquinone silver halide developing agents whichcan be employed in the practice of the invention include, for example:

2-methyl-S-morpholinomethyl hydroquinone 2-methyl-5-pyrrolidinomethylhydroquinone 2-methyl-S-piperidinomethyl hydroquinone 2-morpholinomethylhydroquinone The described aminomethyl hydroquinone compounds can beprepared by a Mannich base condensation reaction, such as described inJournal of Organic Chemistry, Volume 29, pages 2640- (l964). Anothermethod of preparing these compounds is described, for example, inCanadian Pat. No. 766,263 issued Aug. 29, l967.

The described developing agents employed in the practice of theinvention are typically employed in the form of their salts, such astheir acid salts, e.g. their chloride, sulfate or hydrochloride salts oralkali metal salts such as their sodium or potassium salts. Thedescribed developing agents can be employed in their salt form or intheir salt-free form in the practice of the invention.

A processing composition employed in the practice of the invention istypically a viscous processing composition. A wide range of viscositycan be employed. The viscosity can be about 20 to about 100,000centipoise, typically about to about 10,000. Various thickening agentsare suitable in the described processing compositions and processes ofthe invention. Any of those commonly employed in diffusion transferphotographic systems can be employed, as well as those employed inviscous monobaths. These include those described, for example, in U.S.Pat. No. 3,120,795 of Land et al. issued Feb. ll, I964, e.g.hydroxyethyl cellulose and carboxymethyl cellulose.

Suitable viscous monobaths in which the described developing agents canbe employed are set out, for example, in The Monobath Manual by Grant M.Haist (I966), and U.S. Pat. No. 3,392,0l9 ofBarnes et al. issued July 9,1968.

A wide range of silver halide solvents can be employed in the practiceof the invention. Usually the silver halide solvent is sodiumthiosulfate, however, various organic silver halide complexing agents,such as those described in Haist et al., Photographic Science andEngineering, Volume 5, page 198 (1961) and those described in FrenchPat. No. l,3l2,687 issued Nov. 12, 1962 and Belgian Pat. No. 606,559 ofUlrich et al. issued July 26, 1960 and similar agents can be also beused.

Another embodiment of the invention is in a photographic diffusiontransfer process comprising developing a latent image in a photographicsilver halide layer and precipitating an image in an image receiverlayer, the improvement comprising developing the latent image with ahydroquinone silver halide developing agent containing a methyl, ethylor alkoxy group in the position and a carboxyalkyl group containing 4 to9 carbon atoms in the 2 position of the hydroquinone nucleus, asdescribed. A photographic diffusion transfer process according to thisembodiment is typically one wherein the hydroquinone silver halidedeveloping agent is a compound of formula I, as described. Thisphotographic difiusion transfer process is typically a black and whitesilver salt difiusion transfer process.

The process is carried out at a PH which activates the describeddeveloping agents. The activating pH is usually about 10 to about 14with good results being obtained when the pH is above about 12. When thepH of the system is lowered to less than about 8, such as between about8 and about 2, developing activity stops. The optimum pH for anyparticular diffusion transfer system will be influenced by theparticular photographic element, the desired image, various addendaemployed in the processing composition, emulsion and image receiver,processing conditions and the like.

Any development activator can be employed with the described developingagents which provides the desired pH. Typically development activatorswhich are employed are alkali metal hydroxides, such as sodiumhydroxide, potassium hydroxide or lithium hydroxide; however orgaNicdevelopment activators can be employed such as amines, e.g. 2-aminoethanol, 2-methylaminoethanol, 2- dimethylaminoethanol,S-diethylamino-2-pentanol and the like.

A photographic process according to the invention can comprise the stepsof exposing a photographic element comprising a photographic silversalt, especially a photographic silver halide, and a hydroquinone silverhalide developing agent as described, to form a latent image in thephotographic element; developing the latent image with a processingcomposition, at a pH of about 12 to about 14; contacting undevelopedsilver salts in the photographic element with a silver halide solvent toform an imagewise distribution of a silver complex in the unexposedareas of the photographic element; transferring at least part of thissilver complex to an image receiver contiguous to the photographicsilver salt; reducing the silver complex in the presence of developmentnuclei, especially palladium development nuclei, to form a visible imageon the receiver layer; and lowering the pH of the receiver layer tobelow about 8 to form a stable developed image.

Processing conditions, time of development and the like can varydepending upon various factors such as the desired image, the particularcomponents of the described photographic element, processing compositionand image receiver. Typical processing is carried out under normalatmospheric conditions and is completed within about 60 seconds, e.g.within about 10 seconds. Processing temperatures are typically about 20C. to about 30 C. but elevated temperatures can be employed if desiredsuch as temperatures up to about 90C.

The described photographic element, receiving layer and/or processingcomposition can also contain toning agents. Typical toning agents whichcan be employed include, for example, polyvalent inorganic salts asdescribed in US. Pat. No. 2,698,236 of Land issued Dec. 28, 1954; silicaas described in US. Pat. No. 2,698,237 of Land issued Dec. 28, I954 andheterocyclic mercaptans such as mercaptoazoles, e.g. mercaptodiazoles,mercaptotriazoles, mercaptotetrazoles, and the correspondingselenoazoles.

The photographic elements, processing conditions and/or image receiversemployed in the practice of the invention can contain antioxidants, suchas aldehydes-bisulfite condensation products, e.g. sodiumformaldehyde-bisulfite.

Also the image receiver can contain an acid, especially a polymericacid, which can provide lower pH in the image receiver after processing.

The concentration of developing agents used in the practice of theinvention can vary over wide ranges depending upon the particularphotographic and physical variables in the system. For example, thelocation of the developing agent in the system, the photographicelement, processing composition, the desired image, processingconditions and the like will determine a suitable concentration range.Typically, when a developing agent according to the invention isemployed in the photographic element a concentration of about 0.0l toabout 5 mols of developing agent per mol of silver present is employed.This usually corresponds to about l0 to about grams of developing agentper mol of silver or about 10 to about milligrams of developing agentper square foot of support. When a developing agent as described isemployed in the processing composition, the total concentration ofdeveloping agents in the composition is typically about 0.01 percent toabout 10 percent preferably about 1 percent to about 5 percent by weightof the total processing composition.

The following examples are included for a further understanding of theinvention.

EXAMPLE 1 This illustrates the invention.

A gelatin solution containing 66(2,5-dihydroxytolyl) hexanoic acid, alsoknown as Z-carboxypentyl- S-methyl hydroquinone, is coated on apolyethylene coated paper support at 240 milligrams of gelatin persquare foot and 50 milligrams of 6(2,5 dihydroxytolyl) hexanoic acid persquare foot. OVer this is coated a coarse grain silver bromoiodidegelatinpolymer emulsion containing 5 mol percent iodide at milligrams ofsilver per square foot, 320 milligrams of gelatin per square foot and200 milligrams of a copolymer of butyl acrylate with acrylic acidcontaining 90 percent by weight butyl acrylate and I0 percent by weightacrylic acid.

A processing composition is prepared by mixing the following components:

(Natrusol ZSOH. sold by Hercules Powder Co., U.S.A.) Water to l liter Animage receiver is prepared by coating a water-resistant paper supportwith palladium development nuclei dispersed in a polymeric binder. Thedescribed photographic element is sensitometrically exposed. Theprocessing composition, as described, is then squeezed between thephotographic element and the image receiver and the resulting so-calledsandwich is pressed together by running between two rollers. After 30seconds, the so-called sandwich is peeled apart and the resulting imageon the image receiver is observed.

Employing this procedure and the described photographic element,processing composition and image receiver, a good positive image isproduced, on the receiver having a maximum density of 1.54, a minimumdensity of 0.0, a cold black tone and no stain. The relative speed ofthe image is compared to a control rated at 100 at which the samenegative element, processing composition and image receiver are employedwith the exception that t-butyl hydroquinone is employed in place of6(2,5-dihydrozytolyl) hexanoic acid.

EXAMPLE 2 This is a comparative example.

The procedure set out in example 1 is repeated with the exception thatcatechol is employed in place of 6(2,5-dihydroxytolyl) hexanoic acid.The resulting image is vary light, i.e. almost no image is developed.The receiver has a pink stain.

EXAMPLE 3 This is a comparative example.

The procedure set out in example I is repeated with the exception that2,4-diaminophenol dihydrochloride (Amidol) is employed in place of6(2,5-dihydroxytolyl) hexanoic acid. The resulting image has very lowmaximum density and has slight gray stain.

EXAMPLE 4 This is a comparative example.

The procedure set out in example 1 is repeated with the exception thatt-butyl hydroquinone is employed in place of 6(2,5-dihydroxytolyl)hexanoic acid. This is the same as the control noted in example l.Theresulting image has a maximum density of 1.50 and cold black tone buthas slight gray stain.

EXAMPLE 5 This is a comparative example. The procedure set out inexample I is repeated with the exception that a hydroquinone compound ofthe formula:

CHgCHgCHgCOOH is employed in place of 6(2,5-dihydroxytolyl) hexanoicacid. The resulting images has a warm tone, poor stain and minimumdensity is significantly higher.

EXAMPLE 6 The procedure set out in example I is repeated with theexception that Z-methyl- S-morpholinomethyl hydroquinone is employed inplace of 6(2,5 dihydroxtolyl) hexanoic acid in the negative element andI0 grams of a hydroquinone compound of the formula:

also shown as Z-carboxypropyl- S-methyl hydroquinone is employed in thedescribed processing composition.

The resulting image has a maximum density of L45, minimum density of0.0, and cold black tone.

EXAMPLE 7 EXAMPLE 8 The procedure set out in example 1 is repeated withthe exception that 2-methyl- S-morpholinomethyl hydroquinone is employedin place of 6(2,5-dihydroxytolyl) hexanoic acid in the negative elementand 5 grams of Z-carboxypentyl- 5- methyl hydroquinone and 5 grams ofanhydro dihydro piperidino hexose reductone are employed in thedescribed processing composition.

The resulting image on the image receiver has a maximum density of 1.68,a minimum density of 0.0, cold black tone and no stain.

EXAMPLE 9 Similar results are obtained to those set out in example 8employing 2-carboxypropyl- S-methyl hydroquinone in place of2-carboxypentyl- 5-methyl hydroquinone. An in crease in relative speedis observed using a carboxyalkyl group containing two less carbon atoms,i.e. carboxypropyl compared to carboxypentyl.

EXAMPLE 10 Similar results to those set out in example 1 are obtainedemploying 2-carboxypropyl- S-methyl hydroquinone in place of6(2,5-dihydrozytolyl) hexanoic acid.

EXAMPLE 1 1 Similar results to those set out in example 1 are obtainedemploying 2-carboxybutyl- S-methyl hydroquinone in place of6(2,5-dihydroxytolyl) hexanoic acid.

EXAMPLE 12 Similar results to those set out in example 1 are obtainedemploying Z-carboxypropyl- 5,6-dimethyl hydroquinone in place of6(2.5-dihydroxytolyl) hexanoic acid.

EXAMPLE l3 A photographic element is prepared as described in example lwith the exception that the 6(2,5-dihydroxytolyl) hexanoic acid isemployed in the photographic silver halide emulsion. Similar results areobtained.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:

1. ln a photographic product comprising in combination (a) aphotographic element comprising a photographic silver halide, (b) aprocessing composition containing a silver halide solvent and (c) animage receiving layer the improvement comprising in said photographicproduct a hydroquinone silver halide developing agent containing amethyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl groupcontaining 4 to 9 carbon atoms in the 2 position of the hydroquinonenucleus.

2. A photographic product as in claim 1 wherein said hydroquinone silverhalide developing agent is a compound of the formula:

l on

5. A photographic product as in claim 1 wherein said hydroquinone silverhalide developing agent is 6(2,5- dihydroxytolyl) hexanoic acid.

6. A photographic silver halide emulsion comprising photographic silverhalide and a hydroquinone silver halide developing agent containing amethyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl groupcontaining 4 to 9 carbon atoms in the 2 position of the hydroquinonenucleus.

7. A photographic silver halide emulsion as in claim 6 wherein saidhydroquinone developing agent is 6(2,5- dihydroxytolyl) hexanoic acid.

8. A photographic element comprising a support. photographic silverhalide, and a hydroquinone silver halide developing agent containing amethyl, ethyl, or alkoxy group in the 5 position and a carboxyalkylgroup containing 4 to 9 carbon atoms in the 2 position of thehydroquinone nucleus.

9. A photographic element as in claim 8 wherein said hydroquinone silverhalide developing agent is a compound of the formula:

wherein R is methyl, ethyl or alkoxy containing 1 to 5 carbon atoms; nis to R is alkyl containing 1 to 5 carbon atoms.

10. A photographic element as in claim 8 wherein said hydroquinonesilver halide developing agent is 6(2,5- dihydroxytolyl) hexanoic acid.

11. In a photographic processing composition comprising (a) a silverhalide solvent and (b) a silver halide developing agent the improvementcomprising a hydroquinone silver halide developing agent containing amethyl, ethyl, or alkoxy group in the 5 position and a carboxyalkylgroup containing 4 to 9 carbon atoms in the 2 position of thehydroquinone nucleus.

12. A photographic processing composition as in claim 11 wherein saidsilver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.

13. A photographic processing composition as in claim II which is amonobath.

14. A photographic processing composition as in claim H which is aviscous liquid.

15. In a photographic diffusion transfer process comprising developing alatent image in a photographic silver halide layer and precipitating animage in an image receiver layer, the improvement comprising developingsaid latent image with a hydroquinone silver halide developing agentcontaining a methyl, ethyl or alkoxy group in the 5 position and acarboxyalkyl group containing 4 to 9 carbon atoms in the 2 position ofthe hydroquinone nucleus.

16. A photographic diffusion transfer process as in claim 15 whereinsaid hydroquinone silver halide developing agent is a compound of theformula:

I OH

wherein R is methyl, ethyl or alkoxy containing 1 to 5 carbon atoms; nis 0 to 5; R is alkyl containing l to 5 carbon atoms,

17. A photographic diffusion transfer process as in claim 15 whereinsaid hydroquinone silver halide developing agent is6(2,5-dihydroxytolyl) hexanoic acid.

18. A photographic diffusion transfer process as in claim 15 which is ablack and white silver salt diffusion transfer process.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pazgnt, 3 ,61553S Da ed October 26, 1971 v James G. Smith and Dorothy J. Beavers It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 57, before "Amidol", should be .nserted, and after"Amidol", should be inserted.

Column 2, line 32, "Z-carboxypropyl-S-carboxypropy1" should read2carboxybutylS-carboxypropyl Column 3, line 24, "emulsion" should read---emulsions-- Column 5, line 15, "Nen-Ezra" should read --BenEzra-.

Column 6, line 24, "inhibition" should read ---imbibition---. Line 51,after "20", should be inserted.

Column 7, lines 57-58, "methylaminophends; eq. 6-methoxy-2,4diaminophenolascrobic" should read -e.g. 6methoxy2,4- iiaminophenol,methylaminophenols; ascorbic--. Line 60, "Of" should read --of-- Line63, "l-pheny1-3 3-pyrazolidone" should read l-phenyl-3-pyrazolidone--.Lines 63-64, "l-pheny1-4- hydroxymethyl-3pyrazolidone" should read 1-phenyl-4-methyl- 4-hydroxymethy1-3-pyrazolidone-.

Column 8 line 27 that part of the formula reading "Bota4-" should read-Beta, 4- Line 28 "Betametyl" should read ---Beta-methy1 Lines 32-33,"2,5-dihydorxy- 3,4,6'trimethyl cinnamic acid" should read2,5-dihydroxy- 3,4,6-trimethyl cinnamic acid and should be placed on aline separate from and after "2 5-dihydroxy cinnamic acid" Line 62, thatpart of the formula reading "-4-metyl" should read I-methyl Line 74 thatpart of the formula reading "dinydroxy" should read --dihydroXy--.

Column 11, line 26, "orgaNic" should read --organic--.

PAGE 2 mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3 ,615 ,535 Dated October 26 1971 ve or) James G. Smith and DorothyJ. Beavers It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

fi r Column 12 line 26 that part of the formula reading "66 should read6 Line 31, "OVer" should read -Over-- Line 65 "at" (second occurrence)should read -in- Line 68 that part of the formula reading"dihydrozytolyl" should read --dihydroXytolyl-. Line 74, "vary" shouldread --very-.

Column 13, line 35, "images" should read ---image--. Line 41, that partof the formula reading "dihydroxtolyl" should read dihydroxytolyl---.Line 54, "shown" should read --known--- Column 14 line 13 "in crease"should read -increase- Line 22 that part of the formula reading"dihydrozytolyl should read --dihydroxytolyl--.

Signed and sealed this 29th day of August 1972.

(SEAL) Attesb:

EDWARD M.P'LETCHER,JR. ROBERT GOTTSCHALK Alltfjfitlll', Officer-Commissionerof Patents

2. A photographic product as in claim 1 wherein said hydroquinone silverhalide developing agent is a compound of the formula:
 3. A photographicproduct as in claim 1 wherein said photographic product comprises anauxiliary silver halide developing agent.
 4. A photographic product asin claim 1 wherein said processing composition comprises a silver halidedeveloping agent.
 5. A photographic product as in claim 1 wherein saidhydroquinone silver halide developing agent is 6(2,5-dihydroxytolyl)hexanoic acid.
 6. A photographic silver halide emulsion comprisingphotographic silver halide and a hydroquinone silver halide developingagent containing a methyl, ethyl or alkoxy group in the 5 position and acarboxyalkyl group containing 4 to 9 carbon atoms in the 2 position ofthe hydroquinone nucleus.
 7. A photographic silver halide emulsion as inclaim 6 wherein said hydroquinone developing agent is6(2,5-dihydroxytolyl) hexanoic acid.
 8. A photographic elementcomprising a support, photographic silver halide, and a hydroquinonesilver halide developing agent containing a methyl, ethyl, or alkoxygroup in the 5 position and a carboxyalkyl group containing 4 to 9carbon atoms in the 2 position of the hydroquinone nucleus.
 9. Aphotographic element as in claim 8 wherein said hydroquinone silverhalide developing agent is a compound of the formula:
 10. A photographicelement as in claim 8 wherein said hydroquinone silver halide developingagent is 6(2,5-dihydroxytolyl) hexanoic acid.
 11. In a photographicprocessing composition comprising (a) a silver halide solvent and (b) asilver halide developing agent the improvement comprising a hydroquinonesilver halide developing agent containing a methyl, ethyl, or alkoxygroup in the 5 position and a carboxyalkyl group containing 4 to 9carbon atoms in the 2 position of the hydroquinone nucleus.
 12. Aphotographic processing composition as in claim 11 wherein said silverhalide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.
 13. Aphotographic processing composition as in claim 11 which is a monobath.14. A photographic processIng composition as in claim 11 which is aviscous liquid.
 15. In a photographic diffusion transfer processcomprising developing a latent image in a photographic silver halidelayer and precipitating an image in an image receiver layer, theimprovement comprising developing said latent image with a hydroquinonesilver halide developing agent containing a methyl, ethyl or alkoxygroup in the 5 position and a carboxyalkyl group containing 4 to 9carbon atoms in the 2 position of the hydroquinone nucleus.
 16. Aphotographic diffusion transfer process as in claim 15 wherein saidhydroquinone silver halide developing agent is a compound of theformula:
 17. A photographic diffusion transfer process as in claim 15wherein said hydroquinone silver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.
 18. A photographic diffusion transferprocess as in claim 15 which is a black and white silver salt diffusiontransfer process.